Nobody has been paying attention to the rules governing the Republican Party's early caucuses and primaries. They make it inevitable the 12-person field will be winnowed down to a two-way race by March 15. Here's how:

It will take 1,237 delegates to win the Republican nomination in July.

Of the nearly 700 delegates Republicans will parcel out on March 1, 363 of them  52 percent  will be in states that require candidates to reach a threshold of either 20 percent or 15 percent to share in the proportional allocation of delegates. Only two candidates are likely to meet that threshold. The others will win no delegates, even if they win 10 or 12 percent of that state's vote.

Of the next 356 delegates, chosen on March 5, 6, 8 and 12, 215 (or 60 percent) will be selected according to rules setting a 20 percent or 15 percent threshold.

So, before March 15, 578 delegates  about 47 percent of those needed to for the nomination  will have already been selected from threshold states. It is very unlikely a third candidate can reach this level. Right now, for example, neither Jeb Bush nor Marco Rubio nor Chris Christie nor John Kasich nor Ben Carson can point to any single state in which they top 20 percent of the vote.

Before March 15, 478 delegates will be selected from states that do not require a threshold to receive delegates. But, having been excluded from winning delegates in threshold states, a third or fourth candidate would have to win an unrealistically high proportion of those 478 delegates to get back into the race.

If we assume, for the sake of argument, that the two candidates who do pass the threshold  at the moment it would be Donald Trump and Ted Cruz  evenly divide the available delegates in high-threshold states, that would give them each 289 votes. If we further assume that Bush, Rubio, Christie, Carson and Kasich evenly divide half of the delegates chosen in non-threshold states and that Trump and Cruz evenly divide the other half, Trump and Cruz would have about 400 delegates apiece and Bush, Rubio et al. would limp along with only approximately 48 delegates each. Even were one of the candidates excluded by the threshold to win a disproportionate share of the non-threshold delegates, it is hard to see how he could catch up.

Of course, a candidate might get lucky on March 15 and win some of the big winner-take-all states that vote that day, like Florida (99 delegates) or Ohio (66 delegates) but the lead that the two front-runners will have amassed before then is likely too big to overcome.

So all the talk about when Bush or some other candidate will drop out is quite irrelevant. It doesn't matter when reality dawns on them  they will be forced out by the math of the process in the month of March.

Unfortunately, the voters in the March 1 proportional threshold states may not understand all this, with many casting wasted ballots for candidates who have no chance of passing the threshold. In early March, this lack of understanding of how the process works will cost the two front-runners delegate votes, but the voters will soon catch on and vote primarily for one of the top two.

This will create a new dynamic in the GOP nominating process. Now, in a dozen-person beauty contest, we vote for who we like the best. But when it comes down to two candidates, many voters who may not have voted for Trump or Cruz as their first choice will have to choose the lesser of these two "evils."

Ironically, with two such iconoclastic and sui generis people as Trump and Cruz, the nomination could go to the one who is most broadly acceptable  or least widely unacceptable.